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Selecting Cold Cathode Fluorescent Lamp (CCFL)--LCD Backlight

The CCFL (Cold Cathode Fluorescent Lamp) is a light source classified as an electronic component. The CCFL in simplest ter is a gas-discharge light source, which produces its output from a stimulated phosphor coating inside the glass lamp envelope. A CCFL can be described as a transducer converting electrical energy into light energy.

Backlight Reflector:

The Silver Reflector is sputter-coated Ag on polyester film with outstanding optical, mechanical and thermal properties

Lamp ReflectorLCD Backlight Unit

The CCFL or backlight Lamp is mount in side a reflector., an example of a notebook one is shown below, but on some other units there may be up to 4 lamps inside a multiple reflector

Reflector that normally holds the tube inside it, be careful when removing the old tube

How to select the LCD Backlight:

Backlights or ccfl tubes come in various lengths, and the length varies on various brands of lcd.

As an example, the 15" lcd may use between 260-330mm the best way to select a backlight is to measure the one that you presently have

There are three main ways to select the right lamp, which are below.

You need to get as close as you can but not going longer than the one you have (they don't squash down) generally you can get away with between 2-10mm shorter than the original lamp without affecting the quality of the light you receive. even with one slightly shorter, you would only have a tiny slightly less bright corner just below the lamp, but it would still be perfectly usable.

Remember if you select one to long, you will not be able to install it.

How to Measure the Length of LCD Backlight

Method 1: Direct Measure:

This is the best way to get the closed length of lamp possible.

Carefully remove CCFL from Backlight reflector

Slowly pull out rubber cap as show in the picture below

Measure the length of CCFL lamp, Selected the length slightly shorter

For Example: Your old lamp measurement is 320mm, You should use the length of 316mm

Showing the ccfl backlight with the rubber insulator , or cap removed with the pin showing

Method 2

IN-Direct Measure:

LCD Backlight (CCFL Lamps) are normally held on inside of Reflector as picture shown at below.

There are Silicone Rubber Cap on both ends of CCFL Lamps.

The measurement should be from glass to glass( Shown on Photo below) plus the length of one of Silicon Rubber Cap.

For Example: The measurement from glass to glass is 310mm, your Rubber Cap measurement is 5mm (Only Measure one of caps),

Then you correct length should be glass to glass plus 4-5mm one end. Let use 5mm for example.